The present application generally relates to an engine control arrangement for controlling a four-stroke watercraft, and more particularly to an engine management system that warns the user of abnormal oil pressures.
Watercraft, including personal watercraft and jet boats, are often powered by an internal combustion engine having an output shaft arranged to drive a water propulsion device. Occasionally, due to their sporting nature, such watercraft can be operated at planning speeds.
Watercraft often operate within three modes of operation: displacement mode, transition mode and planing mode. During lower speeds, the hull displaces water to remain buoyant; this is the displacement mode. At a particular watercraft speed relative to the water, a portion of the hull rises up from the water and the watercraft begins planing across the water; this is the planing mode. Of course, the transition mode occurs between the displacement mode and the planing mode and involves the range of watercraft speeds that cause a transition between the planing and displacement modes.
Importantly, while the watercraft is planing (i.e., up on plane), the wetted surface area of the watercraft is decreased and the water resistance is substantially reduced. It is during this mode of operation that the watercraft is most often used and the engine is under its most demanding conditions. Oil pressure being vital to the engine operation, should be carefully monitored in order to advise the operator of any lubrication problems.
Certain known oil pressure warning systems set a single threshold for a minimum oil pressure. These types of single low pressure warning systems are set to warn the user when the oil pressure falls below a predetermined value. This predetermined value can be too low and thus fails to provide adequate warning when an engine loses oil pressure at high engine speeds because a dangerously low oil pressure for high engine speeds could still be above the predetermined low oil pressure warning threshold.
Other oil pressure warning systems set the predetermined critical oil pressure value too high to warn the user against a loss of oil pressure at high engine speeds. As a result a warning is falsely communicated to the user when the oil pressure value drops below this predetermined value even though the engine is operating at a lower speed with a low, yet safe oil pressure.
Accordingly, an engine control arrangement has been developed to accurately warn the user of low oil pressure during all speeds of engine operation. The oil pressure warning system is able to determine which oil pressure threshold is appropriate and accurately warns the user when a low oil pressure corresponding to the current watercraft speed is present. A low oil pressure warning system that can adapt to both low and high engine speed characteristics is beneficial in providing the user with a safer, more enjoyable recreational experience.
One aspect of the present invention includes the realization that a sudden automatic decrease in engine speed during operation of a watercraft, can make the operator and passengers uncomfortable. For example, if a watercraft includes a control system which automatically reduces engine speed while the operator is holding the throttle lever at a position corresponding to an elevated watercraft speed, the sudden decrease in watercraft speed can make the operator and any passengers feel uncomfortable. Additionally, if the control system automatically restores engine power, the watercraft can suddenly accelerate, which can also make the operator and any passengers feel uncomfortable.
Thus, another aspect of the present invention is directed to a watercraft comprising a hull with an engine disposed within the hull. The engine includes an engine body defining at least one combustion chamber therein. A fuel delivery system is configured to deliver fuel to the engine body for combustion within the combustion chamber. A lubrication system is configured to circulate lubricant through the engine body. A lubricant pressure sensor is configured to detect a pressure within the lubrication system. Additionally, an engine speed sensor is configured to detect a speed of the engine. The watercraft also includes a controller connected to the lubricant pressure sensor, the engine speed sensor, and the fuel delivery system. The controller is configured to gradually reduce the speed of the engine if the lubricant pressure is below a predetermined pressure.
A further aspect of the present invention is directed to a watercraft having a hull and an engine disposed within the hull. A lubrication system is configured to circulate lubricant through the engine. A lubricant pressure sensor is configured to detect a pressure within the lubrication system. An engine speed sensor is configured to detect a speed of the engine. The watercraft also includes a controller configured to decrease engine speed if the lubricant pressure is below a predetermined pressure. The user controls the power output of the engine with an engine load input device. The controller is configured to continue to operate the engine at a reduced engine speed until the engine load input device is moved to position corresponding to an engine load that is below a predetermined engine load.